Consumer electronics devices are continually getting smaller and, with advances in technology, are gaining ever-increasing performance and functionality. This is clearly evident in the technology used in consumer electronic products and especially, but not exclusively, portable products such as mobile phones, audio players, video players, personal digital assistants (PDAs), various wearable devices, mobile computing platforms such as laptop computers or tablets and/or games devices. Requirements of the mobile phone industry for example, are driving the components to become smaller with higher functionality, lower power consumption and reduced cost.
Micro-electromechanical-system (MEMS) transducers, such as MEMS microphones are finding application in many of these devices. There is therefore also a continual drive to reduce the size and cost of such MEMS microphones and to minimize the area and space taken up with such transducers, for example to enable the use of MEMS transducers that are suitable for embedding in earbuds for noise cancellation or other requirements for acousto-electrical feedback such as speaker linearization.
However the desire for reduction in physical size conflicts with the desire to provide better performance, for example regarding the level of the electronic noise floor. There may be no space available for off-chip capacitors or to provide dual-supplies to allow use of ground as a signal reference voltage or to decouple sensitive nodes with respect to ground. Also system power budgets are progressively getting smaller, and lower power tends, thermodynamically, to imply higher circuit noise levels.
Embodiments of the present disclosure relate to methods and apparatus with improved noise performance, for instance to circuits in which any contribution to noise at an output node that arises due to noise on bias voltage references is at least partly reduced or even eliminated.